Giblets46 information is very good, he has helped me with the same problem. I would suggest that the next thing you do is place a blanking plate (with holes to stop EML coming on) at EGR, clean the MAF (you can buy correct spray at auto store). MAF is simple to remove, unplug connector (make sure you pull out yellow locking tab on connector to remove) remove the two clips either side of the MAF and remove and clean with spray only I do not recommend you poke anything in there. Replace and definately reset ECU (look for thread on here about restting ECU). A good drive at different speeds etc will let the ECU relearn. Mine took a few drives but has now nearly completely cured the stutter, also check all turbo/intercooler hoses after the MAF as if there is a leak or sucking in air after the MAF, this cause problems too. If this doesnt cure then a new MAF could be on the cards. Good Luck.